HP server power up after outage

Posted on 2014-02-18
Last Modified: 2014-04-09
Hi guys and thanks to everyone who can give me some insight here.

I have an enclosed rack with AC units cooling internally.  I have a UPS that gives me about 1 hour of time on a few HP servers and few cisco switches.  The AC units are not on the UPS, so when the power dies, I would like everything to be shutoff rather quickly to avoid any heat issues.

When the power goes out and the UPS moves to battery, the management server sends a script to shutdown the servers.  There is also a PDU which I can script to shutdown each individual power receptacles for the switches, as they cannot power down without being unplugged.  This all functions fine during an outage.  

My issue:

I would like the management server to come back online on its own.  It is a HP DL380 G4 and has the auto power on capability.

In the case of a short outage, which doesnt completely drain the battery, is there a way to make this machine turn itself back on after the load is restored?

Anyone know of a method to make this happen?

Thanks again
Question by:Patrick-NJ
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LVL 18

Assisted Solution

by:Andrej Pirman
Andrej Pirman earned 334 total points
ID: 39869044
Well, one method would be to configure:
- your management server's BIOS under Power State after power fail to be "Always On". This means, that it will shut down on software request (your shutdown script or SNMP message from UPS), but will power up as soon as power STEP from zero-to-normal is detected.
- also your UPS should be configured to shut down itself after shutdown procedure is triggered and shutdown timer elapses. So you do not need to configure each PDU to switch off particular outlets, because after shutdown timer the whole UPS will shut down.

When it will turn on?
Same as management server, UPS switch-on upon ramp voltage from zero-to-normal is detected. But please, TEST this out, since not all UPS behave the same; might also stay off after shutdown, depends on manufacturer's settings.

Another option is to have a (Linux) box, which will automatically power on after UPS comes to life on mains restore. Usually, you can set how much must UPS batteries recharge before UPS passes supply to output receptacles (default should be 30% charged), and at that moment your Linux box will power up.
Then you might have startup script to sequentially power up your servers via Wake-on-LAN feature, server by server. This script could also check PING from the powered up server and proceed with next one only after main server is online (eg.: power on domain controller first, wait until it's online, only then wake other servers up).

Author Comment

ID: 39869070
I have tested the auto power on on my 3 HP servers successfully.  

So basically what you're saying is don't let the battery drain, instead when the management server sees we are running on battery, send its scripts to the other machines, then send a delayed shutdown command to the UPS, and then have the management server shut itself down.

When the load returns, I would assume the UPS would know to power itself back on, and everything would come back to life again.

Am I correct in a nutshell here?

That sounds like a better solution.  I was about to spend another 500 bucks on a management PDU!

Thanks a million.

Author Comment

ID: 39869074
And yes I will test the heck out of it!
LVL 55

Assisted Solution

andyalder earned 166 total points
ID: 39886719
The UPS can probably be set up to shut down the output after a fixed length of time, the UPS itself shouldn't have to be shut down, just the output load segments.
LVL 18

Accepted Solution

Andrej Pirman earned 334 total points
ID: 39893195
Well, shutting down UPS itself has some benefits, for example, when mains return, UPS will wait to charge up to a predefined level (30% by default) then it will power-on. The benefit here is that you have RELIABLE indication of:
- power is back
- batteries are at least 30% full, so UPS can protect of further outages
- and you have a TRIGGER event, which you can hook some action on

One example of POWER-UP action:
- all servers are setup to NOT power up automatically, except main Firewall Linux server
- Linux server has Wake-On-Lan script, which uses correct sequence to power servers up, first main Domain Controller, which all others depend on, and only after it is up and pingable, power on other servers

Another example:
- Only main Domain Controller is set to power up automatically when UPS comes back to life
- Then on Domain Controller you have a post-startup script, which turns on the other servers via Wake-On-Lan

Third example:
- None of the servers is set to power up automatically
- only router and switches get back to life automatically after UPS wakes up
- then you can manually (or via script or other management method) power up servers via built-in iPMI, iRMC or other server management SERVICE LAN port.

Regarding managed outlets on UPS itself, they are usable only for network periferia, switches and routers, for example. But not for servers, because those must shut down gracefully, while switches you may power off by cuting power off.
The same applies to Managed PDU.

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